Television: How TV Works

The "moving parts" of television are two slim beams of electrons that sweep back & forth 15,750 times in each second. One "scans" the optical image of the scene the "pickup tube" is looking at. The other listens carefully, miles away, and paints an almost identical picture on the screen of the receiver.

Ordinary light knocks electrons from certain substances. The stronger the light, the more electrons it detaches. In the television "camera," a lens focuses a picture of the scene on a light-sensitive coating inside the pickup tube's front end. Electrons fly off. They are focused on a thin glass...